Unless there’s a radical change in hardware (which I rather doubt as you seldom see the migration from workstation line to arranger line of a new engine until a few years of profit taking from the WS players has occurred), I see little need for a new Korg arranger.
But there’s much that could be done refining NEXT OS, and repackaging some of the NEXT stuff in more elderly-friendly form and better display form (things like stripping styles gradually down and back, or throwing a little swing into a straight style, etc.).
Unless Korg are willing to change a decades old style format and go to styles with four Intros and Endings and more fills, breaks etc., the actual current panel layout will be fine. So what’s the upside to a new model? It will cost a fortune to tool up for, and will be still mired in this decades old hardware, when an upgrade OS could add better workflow to tempt Yamaha, Roland and Ketron users away from their current arrangers.
Until Korg is ready to go full on next gen, Korg aren’t really going to sell many new arrangers to Korg users, unless they are still on a PA1/2/3x. There just isn’t the hardware to tempt a PA4X user, IMHO. But there’s much in the way of simplifying workflow and making data management less complicated that could appeal to current owners of other brands.
A ‘NEXT 2.0’ probably holds the best chance of widespread sales for Korg until they can figure out how to shoehorn the Nautilus engine for arranger use...
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An arranger is just a tool. What matters is what you build with it..!